title: Molecular evolution of immunoglobulin superfamily genes in primates.
abstract: Genes of the immunoglobulin superfamily (IgSF) have a wide variety of cellular activities. In this study, we investigated molecular evolution of IgSF genes in primates by comparing orthologous sequences of 249 IgSF genes among human, chimpanzee, orangutan, rhesus macaque, and common marmoset. To evaluate the non-synonymous/synonymous substitution ratio (ω), we applied Bn-Bs program and PAML program. IgSF genes were classified into 11 functional categories based on the Gene Ontology (GO) database. Among them, IgSF genes in three functional categories, immune system process (GO:0002376), defense response (GO:0006952), and multi-organism process (GO:0051704), which are tightly linked to the regulation of immune system had much higher values of ω than genes in the other GO categories. In addition, we estimated the average values of ω for each primate lineage. Although each primate lineage had comparable average values of ω, the human lineage showed the lowest ω value for the immune-related genes. Furthermore, 11 IgSF genes, SIGLEC5, SLAMF6, CD33, CD3E, CEACAM8, CD3G, FCER1A, CD48, CD4, TIM4, and FCGR2A, were implied to have been under positive selective pressure during the course of primate evolution. Further sequence analyses of CD3E and CD3G from 23 primate species suggested that the Ig domains of CD3E and CD3G underwent the positive Darwinian selection.
authors.affiliation: Department of Molecular Pathogenesis, Medical Research Institute, and Laboratory of Genome Diversity, Graduate School of Biomedical Science, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Ohtani
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Nakajima
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Akari
authors.forename: Takafumi
authors.initials: T
authors.lastname: Ishida
authors.forename: Akinori
authors.initials: A
authors.lastname: Kimura
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D015703:Antigens, CD / Q000737:chemistry / Q000235:genetics; D015214:Antigens, Differentiation, Myelomonocytic / Q000737:chemistry / Q000235:genetics; D019143:Evolution, Molecular; D005803:Genes, Immunoglobulin; D006801:Humans; D008969:Molecular Sequence Data; D010802:Phylogeny; D011323:Primates / Q000235:genetics* / Q000276:immunology*; D017434:Protein Structure, Tertiary / Q000235:genetics
chemical_list: D015703:Antigens, CD; D015214:Antigens, Differentiation, Myelomonocytic